In the field of regenerative medicine, regeneration of cells, tissues, organs, and the like of a body that are lost due to accidents, disease, and the like, and restoration of functions have been achieved using cultured cells manufactured by culturing cells. Cell tissues that can be manufactured as such cultured cells have a wide variety. An example of the cultured cells includes cardiomyocytes, and the cardiomyocytes are used for heart treatment. Cultured cardiomyocytes themselves have motions corresponding to pulsation. Therefore, in a manufacturing stage of cultured cardiomyocytes, it is necessary to perform quality evaluation of whether the motions are favorable, for example.
In performing such quality evaluation of the cultured cardiomyocytes, visual observation is, for example, performed in current situations. Further, measuring a potential by piercing cultured cardiomyocytes with an electrode has been performed. However, the visual observation is significantly dependent on an observer's subjective view, and it is difficult to obtain an objective and accurate evaluation result. Further, in the case of measuring a potential, the cultured cardiomyocytes come into contact with the electrode, and thus there is a problem that the measurement is not noninvasive. In addition, information that may be quantified on the basis of the measurement of the potential is limited to a pulsation time, and the like. Furthermore, an object to be measured is limited to be placed on an electrode.
Therefore, as a past technology, a configuration is known in which measurement points are set in an imaged screen obtained by photographing a cardiomyocyte, the luminance of the measurement points is automatically measured, and the deformation period of the cardiomyocyte is measured from the measured values (for example, see Patent Document 1).
By the way, pulsation in various regions obtained by an analysis of a phase difference observation moving image of the cultured cardiomyocytes shows cooperative pulsation in a culture duration-related manner. However, the pulsation shows a fluctuation due to administration of various drugs. By detecting such a fluctuation in some way, the drug toxicity, the influence, and the like in drug development can be evaluated in advance, and this has received attention in recent years.
In the past, for example, there has been a method in which an external field potential of cells is detected by an electrode disposed on a bottom of a culture dish, and the pulsation behavior of the cells is captured by a membrane potential change of the cells. Also, there has been a method in which a fluorescent dye, which attaches to calcium and emits light, is put into the cells, and the calcium concentration that fluctuates according to the excitement of the cells (action potential) is detected, so that pulsation rhythm of the cells is detected and an information propagation pattern of the cells is evaluated.